typeck.c

gcc-2.95.3 Linux下最常用的C编译器

	    if (list_length (a1) < list_length (a2))
	      attributes = a2, a2 = a1;

	    for (; a2; a2 = TREE_CHAIN (a2))
	      if (lookup_attribute (IDENTIFIER_POINTER (TREE_PURPOSE (a2)),
				    attributes) == NULL_TREE)
		{
		  a1 = copy_node (a2);
		  TREE_CHAIN (a1) = attributes;
		  attributes = a1;
		}
	  }
      }
  }

  /* Treat an enum type as the unsigned integer type of the same width.  */

  if (TREE_CODE (t1) == ENUMERAL_TYPE)
    t1 = type_for_size (TYPE_PRECISION (t1), 1);
  if (TREE_CODE (t2) == ENUMERAL_TYPE)
    t2 = type_for_size (TYPE_PRECISION (t2), 1);

  if (TYPE_PTRMEMFUNC_P (t1))
    t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
  if (TYPE_PTRMEMFUNC_P (t2))
    t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);

  code1 = TREE_CODE (t1);
  code2 = TREE_CODE (t2);

  /* If one type is complex, form the common type of the non-complex
     components, then make that complex.  Use T1 or T2 if it is the
     required type.  */
  if (code1 == COMPLEX_TYPE || code2 == COMPLEX_TYPE)
    {
      tree subtype1 = code1 == COMPLEX_TYPE ? TREE_TYPE (t1) : t1;
      tree subtype2 = code2 == COMPLEX_TYPE ? TREE_TYPE (t2) : t2;
      tree subtype = common_type (subtype1, subtype2);

      if (code1 == COMPLEX_TYPE && TREE_TYPE (t1) == subtype)
	return build_type_attribute_variant (t1, attributes);
      else if (code2 == COMPLEX_TYPE && TREE_TYPE (t2) == subtype)
	return build_type_attribute_variant (t2, attributes);
      else
	return build_type_attribute_variant (build_complex_type (subtype),
					     attributes);
    }

  switch (code1)
    {
    case INTEGER_TYPE:
    case REAL_TYPE:
      /* If only one is real, use it as the result.  */

      if (code1 == REAL_TYPE && code2 != REAL_TYPE)
	return build_type_attribute_variant (t1, attributes);

      if (code2 == REAL_TYPE && code1 != REAL_TYPE)
        return build_type_attribute_variant (t2, attributes);

      /* Both real or both integers; use the one with greater precision.  */

      if (TYPE_PRECISION (t1) > TYPE_PRECISION (t2))
	return build_type_attribute_variant (t1, attributes);
      else if (TYPE_PRECISION (t2) > TYPE_PRECISION (t1))
        return build_type_attribute_variant (t2, attributes);

      /* Same precision.  Prefer longs to ints even when same size.  */
  
      if (TYPE_MAIN_VARIANT (t1) == long_unsigned_type_node
	  || TYPE_MAIN_VARIANT (t2) == long_unsigned_type_node)
        return build_type_attribute_variant (long_unsigned_type_node,
					     attributes);

      if (TYPE_MAIN_VARIANT (t1) == long_integer_type_node
	  || TYPE_MAIN_VARIANT (t2) == long_integer_type_node)
	{
	  /* But preserve unsignedness from the other type,
	     since long cannot hold all the values of an unsigned int.  */
	  if (TREE_UNSIGNED (t1) || TREE_UNSIGNED (t2))
	     t1 = long_unsigned_type_node;
	  else
	     t1 = long_integer_type_node;
	  return build_type_attribute_variant (t1, attributes);
	}

      if (TYPE_MAIN_VARIANT (t1) == long_double_type_node
	  || TYPE_MAIN_VARIANT (t2) == long_double_type_node)
	return build_type_attribute_variant (long_double_type_node,
					     attributes);	  

      /* Otherwise prefer the unsigned one.  */

      if (TREE_UNSIGNED (t1))
	return build_type_attribute_variant (t1, attributes);
      else
	return build_type_attribute_variant (t2, attributes);

    case POINTER_TYPE:
    case REFERENCE_TYPE:
      /* For two pointers, do this recursively on the target type,
	 and combine the qualifiers of the two types' targets.  */
      /* This code was turned off; I don't know why.
 	 But ANSI C++ specifies doing this with the qualifiers.
 	 So I turned it on again.  */
      {
	tree tt1 = TREE_TYPE (t1);
	tree tt2 = TREE_TYPE (t2);
	tree b1, b2;
	int type_quals;
	tree target;

	if (TREE_CODE (tt1) == OFFSET_TYPE)
	  {
	    b1 = TYPE_OFFSET_BASETYPE (tt1);
	    b2 = TYPE_OFFSET_BASETYPE (tt2);
	    tt1 = TREE_TYPE (tt1);
	    tt2 = TREE_TYPE (tt2);
	  }
	else
	  b1 = b2 = NULL_TREE;

	type_quals = (CP_TYPE_QUALS (tt1) | CP_TYPE_QUALS (tt2));
	tt1 = TYPE_MAIN_VARIANT (tt1);
	tt2 = TYPE_MAIN_VARIANT (tt2);

	if (tt1 == tt2)
	  target = tt1;
	else if (b1)
	  {
	    compiler_error ("common_type called with uncommon member types");
	    target = tt1;
	  }
	else if (tt1 == void_type_node || tt2 == void_type_node)
	  target = void_type_node;
	else if (tt1 == unknown_type_node)
	  target = tt2;
	else if (tt2 == unknown_type_node)
	  target = tt1;
	else
	  target = common_type (tt1, tt2);

	target = cp_build_qualified_type (target, type_quals);

	if (b1)
	  {
	    if (same_type_p (b1, b2)
		|| (DERIVED_FROM_P (b1, b2) && binfo_or_else (b1, b2)))
	      target = build_offset_type (b2, target);
	    else if (binfo_or_else (b2, b1))
	      target = build_offset_type (b1, target);
	  }

	if (code1 == POINTER_TYPE)
	  t1 = build_pointer_type (target);
	else
	  t1 = build_reference_type (target);
	t1 = build_type_attribute_variant (t1, attributes);

	if (TREE_CODE (target) == METHOD_TYPE)
	  t1 = build_ptrmemfunc_type (t1);

	return t1;
      }

    case ARRAY_TYPE:
      {
	tree elt = common_type (TREE_TYPE (t1), TREE_TYPE (t2));
	/* Save space: see if the result is identical to one of the args.  */
	if (elt == TREE_TYPE (t1) && TYPE_DOMAIN (t1))
	  return build_type_attribute_variant (t1, attributes);
	if (elt == TREE_TYPE (t2) && TYPE_DOMAIN (t2))
	  return build_type_attribute_variant (t2, attributes);
	/* Merge the element types, and have a size if either arg has one.  */
	t1 = build_cplus_array_type
	  (elt, TYPE_DOMAIN (TYPE_DOMAIN (t1) ? t1 : t2));
	return build_type_attribute_variant (t1, attributes);
      }

    case FUNCTION_TYPE:
      /* Function types: prefer the one that specified arg types.
	 If both do, merge the arg types.  Also merge the return types.  */
      {
	tree valtype = common_type (TREE_TYPE (t1), TREE_TYPE (t2));
	tree p1 = TYPE_ARG_TYPES (t1);
	tree p2 = TYPE_ARG_TYPES (t2);
	tree rval, raises;

	/* Save space: see if the result is identical to one of the args.  */
	if (valtype == TREE_TYPE (t1) && ! p2)
	  return build_type_attribute_variant (t1, attributes);
	if (valtype == TREE_TYPE (t2) && ! p1)
	  return build_type_attribute_variant (t2, attributes);

	/* Simple way if one arg fails to specify argument types.  */
	if (p1 == NULL_TREE || TREE_VALUE (p1) == void_type_node)
	  {
	    rval = build_function_type (valtype, p2);
	    if ((raises = TYPE_RAISES_EXCEPTIONS (t2)))
	      rval = build_exception_variant (rval, raises);
	    return build_type_attribute_variant (rval, attributes);
	  }
	raises = TYPE_RAISES_EXCEPTIONS (t1);
	if (p2 == NULL_TREE || TREE_VALUE (p2) == void_type_node)
	  {
	    rval = build_function_type (valtype, p1);
	    if (raises)
	      rval = build_exception_variant (rval, raises);
	    return build_type_attribute_variant (rval, attributes);
	  }

	rval = build_function_type (valtype, commonparms (p1, p2));
	rval = build_exception_variant (rval, raises);
	return build_type_attribute_variant (rval, attributes);
      }

    case RECORD_TYPE:
    case UNION_TYPE:
      t1 = TYPE_MAIN_VARIANT (t1);
      t2 = TYPE_MAIN_VARIANT (t2);

      if (DERIVED_FROM_P (t1, t2) && binfo_or_else (t1, t2))
	return build_type_attribute_variant (t1, attributes);
      else if (binfo_or_else (t2, t1))
	return build_type_attribute_variant (t2, attributes);
      else
	{
	  compiler_error ("common_type called with uncommon aggregate types");
	  return error_mark_node;
	}

    case METHOD_TYPE:
      if (TREE_CODE (TREE_TYPE (t1)) == TREE_CODE (TREE_TYPE (t2)))
	{
	  /* Get this value the long way, since TYPE_METHOD_BASETYPE
	     is just the main variant of this.  */
	  tree basetype;
	  tree raises, t3;

	  tree b1 = TYPE_OFFSET_BASETYPE (t1);
	  tree b2 = TYPE_OFFSET_BASETYPE (t2);

	  if (same_type_p (b1, b2)
	      || (DERIVED_FROM_P (b1, b2) && binfo_or_else (b1, b2)))
	    basetype = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (t2)));
	  else
	    {
	      if (binfo_or_else (b2, b1) == NULL_TREE)
		compiler_error ("common_type called with uncommon method types");
	      basetype = TREE_TYPE (TREE_VALUE (TYPE_ARG_TYPES (t1)));
	    }

	  raises = TYPE_RAISES_EXCEPTIONS (t1);

	  /* If this was a member function type, get back to the
	     original type of type member function (i.e., without
	     the class instance variable up front.  */
	  t1 = build_function_type (TREE_TYPE (t1),
				    TREE_CHAIN (TYPE_ARG_TYPES (t1)));
	  t2 = build_function_type (TREE_TYPE (t2),
				    TREE_CHAIN (TYPE_ARG_TYPES (t2)));
	  t3 = common_type (t1, t2);
	  t3 = build_cplus_method_type (basetype, TREE_TYPE (t3),
					TYPE_ARG_TYPES (t3));
	  t1 = build_exception_variant (t3, raises);
	}
      else
        compiler_error ("common_type called with uncommon method types");

      return build_type_attribute_variant (t1, attributes);

    case OFFSET_TYPE:
      /* Pointers to members should now be handled by the POINTER_TYPE
	 case above.  */
      my_friendly_abort (990325);

    default:
      return build_type_attribute_variant (t1, attributes);
    }
}

/* Return 1 if TYPE1 and TYPE2 raise the same exceptions.  */

int
compexcepttypes (t1, t2)
     tree t1, t2;
{
  return TYPE_RAISES_EXCEPTIONS (t1) == TYPE_RAISES_EXCEPTIONS (t2);
}

/* Compare the array types T1 and T2, using CMP as the type comparison
   function for the element types.  STRICT is as for comptypes.  */

static int
comp_array_types (cmp, t1, t2, strict)
     register int (*cmp) PROTO((tree, tree, int));
     tree t1, t2;
     int strict;
{
  tree d1;
  tree d2;

  if (t1 == t2)
    return 1;

  /* The type of the array elements must be the same.  */
  if (!(TREE_TYPE (t1) == TREE_TYPE (t2)
	|| (*cmp) (TREE_TYPE (t1), TREE_TYPE (t2), 
		   strict & ~COMPARE_REDECLARATION)))
    return 0;

  d1 = TYPE_DOMAIN (t1);
  d2 = TYPE_DOMAIN (t2);

  if (d1 == d2)
    return 1;

  /* If one of the arrays is dimensionless, and the other has a
     dimension, they are of different types.  However, it is legal to
     write:

       extern int a[];
       int a[3];

     by [basic.link]: 

       declarations for an array object can specify
       array types that differ by the presence or absence of a major
       array bound (_dcl.array_).  */
  if (!d1 || !d2)
    return strict & COMPARE_REDECLARATION;

  /* Check that the dimensions are the same.  */
  return (cp_tree_equal (TYPE_MIN_VALUE (d1),
			 TYPE_MIN_VALUE (d2))
	  && cp_tree_equal (TYPE_MAX_VALUE (d1),
			    TYPE_MAX_VALUE (d2)));
}

/* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
   or various other operations.  STRICT is a bitwise-or of the
   COMPARE_* flags.  */

int
comptypes (type1, type2, strict)
     tree type1, type2;
     int strict;
{
  register tree t1 = type1;
  register tree t2 = type2;
  int attrval, val;
  int orig_strict = strict;

  /* The special exemption for redeclaring array types without an
     array bound only applies at the top level:

       extern int (*i)[];
       int (*i)[8];

     is not legal, for example.  */
  strict &= ~COMPARE_REDECLARATION;

  /* Suppress errors caused by previously reported errors */
  if (t1 == t2)
    return 1;

  /* This should never happen.  */
  my_friendly_assert (t1 != error_mark_node, 307);

  if (t2 == error_mark_node)
    return 0;

  if (strict & COMPARE_RELAXED)
    {
      /* Treat an enum type as the unsigned integer type of the same width.  */

      if (TREE_CODE (t1) == ENUMERAL_TYPE)
	t1 = type_for_size (TYPE_PRECISION (t1), 1);
      if (TREE_CODE (t2) == ENUMERAL_TYPE)
	t2 = type_for_size (TYPE_PRECISION (t2), 1);

      if (t1 == t2)
	return 1;
    }

  if (TYPE_PTRMEMFUNC_P (t1))
    t1 = TYPE_PTRMEMFUNC_FN_TYPE (t1);
  if (TYPE_PTRMEMFUNC_P (t2))
    t2 = TYPE_PTRMEMFUNC_FN_TYPE (t2);

  /* Different classes of types can't be compatible.  */
  if (TREE_CODE (t1) != TREE_CODE (t2))
    return 0;

  /* Qualifiers must match.  */
  if (CP_TYPE_QUALS (t1) != CP_TYPE_QUALS (t2))
    return 0;
  if (strict == COMPARE_STRICT 
      && TYPE_FOR_JAVA (t1) != TYPE_FOR_JAVA (t2))
    return 0;

  /* Allow for two different type nodes which have essentially the same
     definition.  Note that we already checked for equality of the type
     qualifiers (just above).  */

  if (TYPE_MAIN_VARIANT (t1) == TYPE_MAIN_VARIANT (t2))
    return 1;

  /* ??? COMP_TYPE_ATTRIBUTES is currently useless for variables as each
     attribute is its own main variant (`val' will remain 0).  */
#ifndef COMP_TYPE_ATTRIBUTES
#define COMP_TYPE_ATTRIBUTES(t1,t2)	1
#endif

  if (strict & COMPARE_NO_ATTRIBUTES)
    attrval = 1;
  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  else if (! (attrval = COMP_TYPE_ATTRIBUTES (t1, t2)))
     return 0;

  /* 1 if no need for warning yet, 2 if warning cause has been seen.  */
  val = 0;

  switch (TREE_CODE (t1))
    {
    case TEMPLATE_TEMPLATE_PARM:
      if (TEMPLATE_TYPE_IDX (t1) != TEMPLATE_TYPE_IDX (t2)
	  || TEMPLATE_TYPE_LEVEL (t1) != TEMPLATE_TYPE_LEVEL (t2))
	return 0;
      if (! comp_template_parms (DECL_TEMPLATE_PARMS (TYPE_NAME (t1)),
				 DECL_TEMPLATE_PARMS (TYPE_NAME (t2))))
	return 0;
      if (!TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (t1) 
	  && ! TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (t2))
	return 1;
      /* Don't check inheritance.  */
      strict = COMPARE_STRICT;
      /* fall through */

    case RECORD_TYPE:
    case UNION_TYPE:
      if (TYPE_TEMPLATE_INFO (t1) && TYPE_TEMPLATE_INFO (t2)
	  && (TYPE_TI_TEMPLATE (t1) == TYPE_TI_TEMPLATE (t2)
	      || TREE_CODE (t1) == TEMPLATE_TEMPLATE_PARM))
	val = comp_template_args (TYPE_TI_ARGS (t1),
				  TYPE_TI_ARGS (t2));
    look_hard:
      if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2))
	{
	  val = 1;
	  break;
	}
      if ((strict & COMPARE_RELAXED) && DERIVED_FROM_P (t2, t1))
	{
	  val = 1;
	  break;
	}
      break;